1. Field of Invention
Embodiments of the invention relate generally to electrical power distribution equipment. More specifically, at least one embodiment relates to an apparatus and a method for scalable power distribution.
2. Discussion of Related Art
Centralized data centers for computer, communications and other electronic equipment have been in use for a number of years. More recently, with the increasing use of the Internet, large scale data centers that provide hosting services for Internet service providers (“ISPs”), application service providers (“ASPs”) and Internet content providers are becoming increasingly popular. Typical centralized data centers contain numerous racks of equipment that require power, cooling and connections to communication facilities.
In general, centralized data centers have a power distribution system configured to avoid power outages because the data centers include a high percentage of critical loads without which an enterprise may be unable to operate. Often, an uninterruptible power supply (“UPS”) is employed in the power distribution system to ensure that equipment receives continuous power and avoids any power outages. Typical power distribution systems include racks of equipment, for example, servers and the like that are located in the data center. Generally, a plurality of power distribution circuits are provided where each circuit supplies power to one or more electrical loads (e.g., servers, cooling systems, lighting circuits, etc.) via a circuit breaker. These systems generally include racks in which the circuit breakers are installed (i.e., power distribution units) or alternatively racks that include an electrical panel board which is in general similar in design to the panel boards that are found in ordinary commercial facilities.
Problems with these approaches include the fact that the installation or removal of a circuit breaker from the panel board or power distribution unit requires that a skilled individual (i.e., an electrician) perform the installation or removal in close proximity to energized electrical circuits which may include exposed electrical connections and/or conductors. Alternatively, the power distribution equipment can be de-energized to facilitate the installation or removal of one or more circuit breakers. Of course, given the critical nature of the electrical load in the data centers, even these scheduled outages are undesirable.
Some existing approaches attempt to minimize power interruptions resulting from the connection of new power distribution circuits by providing pre-fabricated plug-in power cables whereby a first end of the cable includes a connector that can be plugged into an output of a circuit breaker at the power distribution unit and a second end that can be connected to an electrical load. Although this approach may allow an electrical load to be safely connected to the circuit breaker without de-energizing the entire power distribution unit (e.g., connected with the panel board energized but without requiring any “hot work”), it requires that the cable lengths be pre-determined. In addition, such systems may not be scalable, that is, each panel board or other power distribution unit may not be configured for the correct size or quantity of circuits and corresponding circuit breakers.
As one alternative, some current systems allow a user to order a preconfigured power distribution unit that includes a main breaker with a fixed rating and a plurality of branch circuit breakers each with a pre-selected current rating. Given the dynamic nature of the electrical load that may be included in the data center, for example, the addition of one or more computers, servers, chillers, etc., the preceding approach does not provide an advantage except in the rare instance where the power distribution unit supplies a known, fixed electrical load. That is, the preceding approach is only effective where the designer and/or user of the distribution system can accurately identify the electrical loading and power distribution requirements of the facility at the time of installation. Generally, it is unrealistic to expect that the designer and/or user will accurately predict the electrical loading (e.g., the quantity of distribution circuits and their maximum loading) given the dynamic nature of facility design, power distribution systems and the connected electrical load. As a result, preconfigured power distributions are often specified with substantial excess capacity that is never used.